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    <meta charset="UTF-8">
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    <title>Document</title>
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    <script>
        var a = 4;

        function b(x, y, a) {
            console.log(a); // 3
            arguments[2] = 10;
            console.log(a); // 10
        }
        a = b(1, 2, 3);
        console.log(a); // undefined
    </script>
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